I have recently ripped down old lath and plaster ceilings and replaced them and double boarded. Above this, is a large loft conversion (converted years ago - with little or no regs). The issue is, that the weight of this has caused a lot of the ceiling joists (4x2) to bend in the larger rooms (5x5 meters). The worst was probably a few inches lower than the outer joists, which as a result, creates a sloping floor in the loft space.

In hindsight, I should have strengthened these prior to re-boarding, but was limited on time. Also, without tearing out the whole loft conversion, it seemed a mammoth task to add in new beams the full length.

I want to chipboard out the loft space (currently thin floor boards).

My thoughts are:

1. to level out the sloping loft floor with plastic noggins on top of the existing thin floorboards. Then chipboard over the top. I know this will add more weight but may spread the load of anything that is up there? - is this the best way to level it (without a leveling compound)?

2. Add battons to the sides of existing joists, at the sections I can access?

3. Insulate between the joists (currently nothing), by lifting the floor boards. To help with heat retention. Would I be better off with celotex (or equivalent) or use a loft roll / rockwool (or equivalent)?

Any other Ideas of what I could do - without getting a full loft conversion with steals and new 8 x 2 timber beams?

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